This invention relates to dilatation catheters. Such catheters are well known. They are commonly used for example, in angioplasty procedures to dilate blood vessels. They comprise a catheter shaft with an inflatable balloon located near the leading end of the catheter when it is inserted into the body of the patient. This end is commonly known as the distal end. This balloon is inflated in order to effect the desired dilatation of the blood vessel. When this procedure is completed, the balloon is deflated and the catheter is removed from the body.
Hitherto, the balloon of such a catheter has consisted of an inflatable sleeve or bulb fitted on the outside of the shaft at or near the distal end. The balloon is inflated by the application of fluid passing from within the shaft. It is obviously desirable that the balloon does not inflate to an extent which would damage the blood vessel of the patient and it is an object of the present invention to provide a dilatation catheter with an inflatable portion or balloon which cannot expand beyond acceptable limits and which, when the inflatable portion is deflated, has a smooth surface flush with the shaft.